A Chemical Ionization Mass Spectrometer For Continuous Underway Shipboard Analysis Of Dimethylsulfide In Near-Surface Seawater

Authors

Eric S. Saltzman, University of California - IrvineFollow
Warren J. De Bruyn, Chapman UniversityFollow
M. J. Lawler, University of California - Irvine
Christa Marandino, University of California - IrvineFollow
C. A. McCormick, University of California - Irvine

Document Type

Article

Publication Date

2009

Abstract

A compact, low-cost atmospheric pressure, chemical ionization mass spectrometer ('mini-CIMS') has been developed for continuous underway shipboard measurements of dimethylsulfide (DMS) in seawater. The instrument was used to analyze DMS in air equilibrated with flowing seawater across a porous Teflon membrane equilibrator. The equilibrated gas stream was diluted with air containing an isotopically-labeled internal standard. DMS is ionized at atmospheric pressure via proton transfer from water vapor, then declustered, mass filtered via quadrupole mass spectrometry, and detected with an electron multiplier. The instrument described here is based on a low-cost residual gas analyzer (Stanford Research Systems), which has been modified for use as a chemical ionization mass spectrometer. The mini-CIMS has a gas phase detection limit of 220 ppt DMS for a 1 min averaging time, which is roughly equivalent to a seawater DMS concentration of 0.1 nM DMS at 20 degrees C. The mini-CIMS has the sensitivity, selectivity, and time response required for underway measurements of surface ocean DMS over the full range of oceanographic conditions. The simple, robust design and relatively low cost of the instrument are intended to facilitate use in process studies and surveys, with potential for long-term deployment on research vessels, ships of opportunity, and large buoys.

Comments

This article was originally published in Ocean Science, volume 5, issue 4, in 2009. DOI: 10.5194/os-5-537-2009

Recommended Citation

Saltzman, E. S., W. J. De Bruyn, M. J. Lawler, C. A. Marandino, and C. A. McCormick. "A chemical ionization mass spectrometer for continuous underway shipboard analysis of dimethylsulfide in near-surface seawater." Ocean Science 5.4 (2009): 537-546. doi: 10.5194/os-5-537-2009

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The authors

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This work is licensed under a Creative Commons Attribution 3.0 License.